Method and system for server-side handling of a low-power client in a wide area network

ABSTRACT

A CMTS may receive a request that a network device be permitted to enter a power-saving mode of operation. In response, the CMTS may enter a power-saving mode of operation wherein MAC management messages, transmission opportunities for the sleeping network device, and/or contention periods on one or more channels occur at independently determinable intervals. The CMTS may then transmit a message granting the network device permission to enter the power-saving mode of operation. The CMTS may start a sleep timer upon transmitting the MAC management message and may deregister the network device if no communication is received from the network device prior to expiration of the sleep timer. The CMTs may buffer traffic destined for the network device in a buffer of the CMTS while the network device is in the power-saving mode of operation, and may wake the network device upon the amount of buffered traffic reaching a threshold.

CLAIM OF PRIORITY

This patent application is a continuation of U.S. application Ser. No.13/553,195, filed Jul. 19, 2012, now U.S. Pat. No. 8,687,535, whichmakes reference to, claims priority to and claims benefit from U.S.Provisional Patent Application Ser. No. 61/547,663 filed on Oct. 14,2011, now expired; U.S. Provisional Patent Application Ser. No.61/555,550 filed on Nov. 4, 2011, now expired; and U.S. ProvisionalPatent Application Ser. No. 61/569,346 filed on Dec. 12, 2011, nowexpired.

Each of the above applications is hereby incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

Certain embodiments of the invention relate to networking. Morespecifically, certain embodiments of the invention relate to a methodand system for server-side handling of a low-power client in a wide areanetwork.

INCORPORATION BY REFERENCE

This patent application also makes reference to:

-   U.S. patent application Ser. No. 13/485,034 entitled “Method and    System for Server-Side Message Handling in a Low-Power Wide Area    Network,” and filed on May 31, 2012;-   U.S. patent application Ser. No. 13/553,328 entitled “Method and    System for Client-Side Message Handling in a Low-Power Wide Area    Network,” and filed on the same date as this application; and-   U.S. patent application Ser. No. 13/553,175 entitled “Method and    System for a Low-Power Client in a Wide Area Network,” and filed on    the same date as this application.

Each of the above applications is hereby incorporated herein byreference in its entirety.

BACKGROUND OF THE INVENTION

Existing wide area networks consume too much power. Further limitationsand disadvantages of conventional and traditional approaches will becomeapparent to one of skill in the art, through comparison of such systemswith some aspects of the present invention as set forth in the remainderof the present application with reference to the drawings.

BRIEF SUMMARY OF THE INVENTION

A system and/or method is provided for server-side handling of alow-power client in a wide area network, substantially as illustrated byand/or described in connection with at least one of the figures, as setforth more completely in the claims.

These and other advantages, aspects and novel features of the presentinvention, as well as details of an illustrated embodiment thereof, willbe more fully understood from the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an exemplary DOCSIS network which may take advantage ofaspects of the invention.

FIG. 2 depicts a cable modem as an example of customer premise equipment(CPE).

FIG. 3 depicts a cable set-top box as an example of customer premiseequipment (CPE).

FIG. 4 depicts a cable gateway as an example of customer premiseequipment (CPE).

FIGS. 5A and 5B illustrate a transition to a state in which MACmanagement messages are transmitted at predetermined intervals.

FIGS. 6A and 6B illustrate activity on a network channel before andduring a CPE entering a power-saving state.

FIG. 7 is a flowchart illustrating exemplary steps implemented in a CMTSfor handling a client device which supports a power-saving mode ofoperation.

FIG. 8 is a flowchart illustrating exemplary steps implemented in a CMTSfor handling a client device which supports a power-saving mode ofoperation.

DETAILED DESCRIPTION OF THE INVENTION

As utilized herein the terms “circuits” and “circuitry” refer tophysical electronic components (i.e. hardware) and any software and/orfirmware (“code”) which may configure the hardware, be executed by thehardware, and or otherwise be associated with the hardware. As utilizedherein, “and/or” means any one or more of the items in the list joinedby “and/or”. As an example, “x and/or y” means any element of thethree-element set {(x), (y), (x, y)}. As another example, “x, y, and/orz” means any element of the seven-element set {(x), (y), (z), (x, y),(x, z), (y, z), (x, y, z)}. As utilized herein, the terms “block” and“module” refer to functions than can be implemented in hardware,software, firmware, or any combination of one or more thereof. Asutilized herein, the term “exemplary” means serving as a non-limitingexample, instance, or illustration. As utilized herein, the term “e.g.,”introduces a list of one or more non-limiting examples, instances, orillustrations.

FIG. 1 depicts an exemplary DOCSIS network which may take advantage ofaspects of the present invention. Shown in FIG. 1 is a terrestrialtelevision antenna 102, a satellite dish 104, an Internet Protocol (IP)network 106, a headend 108, a wide area network (e.g., hybridfiber-coaxial (HFC) network) 118, a gateway 120, end systems 126 a and126 b (e.g., computers), end systems 128 a and 128 b (e.g.,televisions), a cable modem 122 b, and a set-top box 124 b. The headend108 comprises a switch 110, a video modulator 112, a cable modemtermination system (CMTS) 114, and a splitter/combiner 116. The gateway120 may be an instance of the gateway 120 described below with respectto FIG. 4, and may comprise a cable modem module 122 a, and a set-topbox module 124 a. Each of cable modems 122 a and 122 b may be aninstance of the cable modem module 122 described with respect to FIG. 2.Each of set-top boxes 124 a and 124 b may be an instance of the set-topbox module 124 described with respect to FIG. 3.

For downstream traffic, the headend 108 may receive television signalsvia the antenna 102 and the satellite dish 104, and may receive data viathe IP network 106. The switch 110 may convey the television signals tothe video modulator 112 and the data to the CMTS 114. The videomodulator 112 may modulate the received television signals onto acarrier. The CMTS 114 may modulate the received data onto a carrier. Thesplitter/combiner 116 may combine the outputs of the video modulator 112and the CMTS 114 and output the combined signal onto the wide areanetwork (WAN) 118 for distribution to CPE. The cable modems 122 a and122 b may process the portion of the combined signal that carries thedata from the CMTS 114, and the set-top box modules 124 a and 124 b mayprocess the portion of the combined signal that carries the video fromthe video modulator 112.

For upstream data, the end systems 126 a and 126 b may transmit packetsto the cable modem 122 a and 122 b, respectively, which may thenmodulate the packets onto a carrier for transmission via the WAN 118.The splitter/combiner 116 may then convey the data to the CMTS 114. TheCMTS 114 may process the data signals (e.g., verify that they came froma registered cable modem) and convey the data to the IP network 106.

The CMTS 114 may manage connections to the cable modems 122 a and 122b.This may include, for example: participating in ranging operations tocontrol the power at which the cable modems 122 a and 122 b transmit;forwarding of dynamic host configuration protocol (DHCP) messagesbetween a DHCP server and the cable modems 122 a and 122 b; forwardingof time of day messages between a time of day server and the cablemodems 122 a and 122 b; and managing registration of the cable modems122 a and 122 b to grant the cable modems network (e.g., Internet)access. The registration process for a cable modem 122 may comprise thecable modem 122 sending a registration request along with itsconfiguration settings, and the CMTS 114 accepting or rejecting thecable modem based on the configuration settings. The registrationprocess may additionally comprise an exchange of security keys,certificates, or other authentication information.

Conventionally, after a cable modem has successfully registered with theCMTS 114, the CMTS 114 will deregister the cable modem if the cablemodem does not communicate with the CMTS 114 for a predetermined periodof time. Accordingly, aspects of the present invention may enable acable modem 122 and the CMTS 114 to coordinate the cable modem 122operating in a low-power mode (“sleeping”) without being deregistered bythe CMTS 114. Such coordination between the cable modem 122 and the CMTS114 may be accomplished through communication of one or more messages,as is described, for example, with respect to FIG. 7A and/or FIG. 7B.

In an exemplary embodiment of the invention, the CMTS 114 may compriseone or more buffers for storing data that is waiting to be transmittedto a CPE which is operating in a low-power mode of operation.

Aspects of the invention may enable media access planning in adownstream direction. In this regard, the CMTS 114 may communicate(e.g., via one or more special messages) with CPEs (e.g., cable modems)that it serves to coordinate when and how (e.g., on which channel(s))the CMTS 114 will communicate with the CPEs. Downstream planning mayenable a CPE to sleep until the next time at which the plan requires itto listen on the channel(s).

Aspects of the invention may enable the CMTS 114 to dedicate a timeslotfor the transmission of special messages to one or more sleeping CPEs.The timeslot may occur at intervals that are independently determinableby the one or more CPEs. That is, duration of the intervals can bedetermined by each of the one or more CPEs without those devices havingto listen for messages outside of the dedicated timeslot. In an exampleembodiment, such an interval may be of a predetermined duration that ismade known to the one or more CPEs prior to the start of the timeslot.In another example embodiment, the duration of such an interval may bedetermined independently by each of the one or more CPEs while theinterval is in progress. In such an embodiment, the determination may bebased on context information (e.g., time of day, previous traffic, etc.)available to the one or more CPEs. Such a scheme may be analogous to anunsolicited grant service, but in the downstream direction. Accordingly,a CPE (e.g., cable modem 122, set-top box 124, or gateway 120) may sleepfor one or more of the intervals between occurrences of the timeslot,wake up and listen to the channel during the timeslot, and then go backto sleep. Such dedicated timeslots in the downstream direction maycoincide in time with, and/or have an independently determinable timerelationship (e.g., a predetermined, fixed time relationship) to,unsolicited grants in the upstream direction. In this manner, if thereis no upstream activity during the corresponding unsolicited grant, thenadjustments may be made to, for example, the duration of the timeslot,the interval between occurrences of the timeslot, etc. The specialmessages communicated during occurrences of the timeslot may, forexample, contain wake up messages. As another example, the specialmessages communicated during occurrences of the timeslot may comprisedata communicated to and/or from “always on” end systems (e.g.,appliances, utility meters, etc.) that may need to communicate over theWAN via a CPE even when the CPE is in a power-save mode.

In an embodiment of the invention, one or more logical channels may bededicated for the communication of special messages (e.g., messagespertaining to power management) and/or for the communication of trafficto “always-on” end systems, even when a CPE via which the “always-on”end system communicates is in a power-saving mode. For example, insystems utilizing DVB-C2 or DVB-T2, such traffic can be mapped to adedicated physical layer pipe.

FIG. 2 depicts a cable modem as an example of customer premise equipment(CPE). The cable modem 122 comprises a physical layer transceiver (PHY)module 202, DOCSIS medium access controller (MAC) module 204, EthernetMAC/PHY module 206, a TCP/IP stack module 208, a conditional accessmodule 210, and a host 218 comprising a CPU 216 and memory module 214which interoperate to execute applications/processes 212.

The PHY module 202 may be operable to receive digital signals from theMAC 204, generate corresponding analog symbols, and transmit the symbolsonto the WAN 118. Similarly, the PHY module 202 may be operable toreceive analog symbols over the WAN 118, convert the symbols to digitalsignals, and convey the digital signals to the MAC module 204. The PHYmodule 202 may be an instance of the PHY module 500 described below withrespect to FIG. 5A. The MAC module 204 may be operable to implementDOCIS media access control protocol(s) for regulating when and/or howthe cable modem 122 transmits on the WAN 118. The Ethernet MAC/PHYmodule 206 may be operable to implement Ethernet physical layer and datalink layer protocols such that the cable modem 220 may transmit andreceive via an Ethernet local area network (LAN). The TCP/IP stackmodule 208 may be operable to implement functionality of OSI layers 3and higher layers to enable the host 218 to communicate via the WAN 118and/or the LAN. The conditional access module 210 may be operable toprevent the host from transmitting and/or receiving DOCSIS traffic viathe WAN 118 if the cable modem 122 is not subscribed to such services.The CPU 216 may execute instructions stored in the memory module 214 andstore run-time data in the memory module 214 to execute variousprocesses and/or applications (e.g., an operating system).

In operation, if and/or when the cable modem 122 may operate in apower-saving mode (a mode in which one or more of its componentsnormally used for transmission and/or reception are powered down) may becontrolled based on a variety of factors such as, for example,statistics and/or patterns of traffic in the network, number and/ortypes of devices in the premises served via the modem 122, and/or inputfrom a network administrator and/or a user in the premises served viathe modem 122. Such components may comprise a media access controller(or portions thereof) of the cable modem 122 and/or a PHY (or portionsthereof) of the cable modem 122. Transitions into and/or out of apower-saving mode may be coordinated via an exchange of messages suchas, for example, described below in FIGS. 7A and 7B.

FIG. 3 depicts a cable set-top box as an example of customer premiseequipment (CPE). The set-top box 124 comprises a physical layertransceiver (PHY) module 302, a conditional access module 304, an MPEGdecoder module 306, audio digital-to-analog converter (DAC) module 308,and video encoder module 310.

The PHY module 302 may be operable to receive analog symbols over theWAN 118, convert the symbols to digital signals, and convey the digitalsignals to the MAC module 204. The PHY module 302 may be an instance ofthe PHY module 500 described below with respect to FIG. 5A. Theconditional access module 304 may be operable to prevent the set-top box124 from decoding audio/video content to which it is not subscribed. TheMPEG decoder module 306 may be operable to decode MPEG streams carriedin the signal received via the WAN 118. The Audio DAC module 308 may beoperable to convert one or more digital audio signals output by the MPEGdecoder 306 into an analog signal for output to one or more speakers.The video encoder 310 may be operable to output one or more digitalvideo signals output by the MPEG decoder 306 according to one or morevideo protocols such as HDMI or DisplayPort.

In operation, if and/or when the set-top box 124 may operate in apower-saving mode (a mode in which one or more of its componentsnormally used for transmission and/or reception are powered down) may becontrolled based on a variety of factors such as, for example,statistics and/or patterns of traffic in the network, number and/ortypes of devices in the premises served via the set-top box 124, and/orinput from a user in the premises served via the set-top box 124. Suchcomponents may comprise a media access controller (or portions thereof)of the set-top box 124 and/or a PHY (or portions thereof) of the set-topbox 124. Transitions into and/or out of a power-saving mode may becoordinated via an exchange of messages such as, for example, describedbelow in FIGS. 7A and 7B.

FIG. 4 depicts a cable gateway as an example of customer premiseequipment (CPE). The gateway 120 comprises a PHY module 402, a DOCSISMAC module 404, a conditional access module 406, a host controllermodule 408, an Ethernet MAC/PHY module 410, an MPEG decoder module 412,a video encoder module 414, and an audio DAC module 416.

The PHY module 402 may be operable to receive digital signals from theMAC 404, generate corresponding analog symbols, and transmit the symbolsonto the WAN 118. Similarly, the PHY module 402 may be operable toreceive analog symbols over the WAN 118, convert the symbols to digitalsignals, and convey the digital signals to the MAC module 404. The PHYmodule 402 may be an instance of the PHY module 500 described below withrespect to FIG. 5A. The MAC module 404 may be operable to implementDOCIS media access control protocol(s) for regulating when and/or howthe gateway 120 transmits on the WAN 118. The conditional access module406 may be operable to prevent the gateway 120 from decoding audio/videocontent and/or data to which it is not subscribed. The host controllermodule 408 may be operable to implement OSI layer 3 and higher OSIlayers to enable communication between the WAN 118 and the LAN networkvia the Ethernet MAC/PHY module 410. The Ethernet MAC/PHY module 410 maybe operable to implement Ethernet physical layer and data link layerprotocols such that the gateway 120 may transmit and receive via anEthernet local area network (LAN). The MPEG decoder module 412 may beoperable to decode MPEG streams carried in the signal received via theWAN 118. The Audio DAC module 416 may be operable to convert one or moredigital audio signals output by the MPEG decoder 412 into an analogsignal for output to one or more speakers. The video encoder 414 may beoperable to output one or more digital video signals output by the MPEGdecoder 412 according to one or more video protocols such as HDMI orDisplayPort.

In operation, if and/or when the gateway 120 may operate in apower-saving mode (a mode in which one or more of its componentsnormally used for transmission and/or reception are powered down) may becontrolled based on a variety of factors such as, for example,statistics and/or patterns of traffic in the network, number and/ortypes of devices in the premises served via the gateway 120, and/orinput from a user in the premises served via the gateway 120. Suchcomponents may comprise a media access controller (or portions thereof)of the gateway 120 and/or a PHY (or portions thereof) of the gateway120. Transitions into and/or out of a power-saving mode may becoordinated via an exchange of messages such as, for example, describedbelow in FIGS. 7A and 7B.

FIGS. 5A and 5B illustrate a transition to a state in which MACmanagement messages are transmitted at predetermined intervals.Referring to FIG. 5A and 5B, there is shown MAP messages n-6 through ncommunicated at non-independently-determinable intervals. That is, fromthe cable modem's perspective the duration of each of the intervals(t3-t1), (t5-t3), (t7-t5), and (t9-t7) are rand and, thus the cablemodem has to continuously listen. At time t13, however, the cable modemsends a request that it be permitted to enter a power-saving mode ofoperation. The message may be, for example, a MAC management messagewherein the contents of its Type Value field are uniquely associatedwith a sleep request.

At time t15, the CMTS responds with a message granting the cable modempermission to sleep. The message may be, for example, a MAC managementmessage wherein the contents of its Type Value field are uniquelyassociated with a message granting permission to sleep. The CMTS maydetermine to grant the request based on various considerations such asnetwork traffic, type(s) of devices in the network. The message grantingthe sleep request may also include parameters such as how long the cablemodem is permitted to sleep, whether the cable modem must listen formessages while it is sleeping, the timing of MAC management messages,contention periods, and/or timeslots reserved for the cable modem whilethe modem is sleeping, etc.

Subsequent to the grant at time t15, the CMTS may send MAP messages atindependently determinable intervals until the modem transitions out ofthe power-saving mode back to a normal mode of operation. That is, theduration of each of the intervals (t19-t17), (t21-t19), and (t23-t21) iseither predetermined and known to the cable modem prior to the start ofthe interval, or determinable from context during the interval (withoutthe cable modem having to listen during the interval). In the exampleembodiment depicted, each of the intervals (t19-t17), (t21-t19), and(t23-t21) are of a common, predetermined duration. While in thepower-saving mode, the cable modem may track time such that it knowswhen the next MAP message will be sent. In this manner, should the cablemodem desire, it can transition out of the power-saving state just intime to hear the MAP message, receive and process the MAP message, andthen return to the power-saving state immediately thereafter.

FIGS. 6A and 6B illustrate activity on a network channel before andduring a CPE entering a power-saving state. Shown in these two figuresis activity on an exemplary WAN channel. During timeslots 602, MACmanagement messages, such as UCD, SYNC, and/or MAP messages, may betransmitted by the CMTS. The timeslots 804 may correspond to, forexample, contention periods and/or timeslots reserved for a particularCPE. In FIG. 6A, the timeslots 602 occur atnon-independently-determinable intervals. That is, from the cablemodem's perspective, the duration of each of the intervals Δ1, Δ2, andΔ3 are of varying durations. Similarly, timeslots 604 occur atnon-independently-determinable intervals. That is, Δ4, Δ5, and Δ6 israndom and, thus the cable modem has to continuously listen. In FIG. 6B,after the CPE has been permitted to enter a power-saving mode ofoperation, the timeslots 602 and 604 occur at predetermined intervals.That is, the cable modem can independently determine the duration ofeach of Δ8-Δ13 and power off and on its receiver accordingly.

FIG. 7 is a flowchart illustrating exemplary steps implemented in a CMTSfor handling a client device which supports a power-saving mode ofoperation. Subsequent to start step 702, in step 704, a cable modemconnects to the CMTS and the two devices exchange messages resulting inthe CMTS registering the cable modem. In step 706, the CMTS receives asleep request message from the CMTS. The message may be, for example, aMAC management message wherein the contents of its Type Value field areuniquely associated with a sleep request. In step 708, the CMTS decideswhether to grant the sleep request. The CMTS may make the decision basedon, for example, past network traffic patterns and/or statistics,expected future traffic, time of day, type and/or number of devicesconnected to the CMTS via the cable modem, a level of service to whichthe cable modem is subscribed, an amount of bandwidth that the cablemodem has used in the billing period or has left to use in the billingperiod, or any other suitable considerations.

In step 710, if the CMTS denies the cable modem permission to transitionto the low-power mode, then the exemplary steps advance to step 720. Instep 720, the CMTS operates in a mode of operation in which timeslots602 and/or 604 (FIGS. 6A and 6B) do not occur atindependently-determinable intervals or times.

Returning to step 710, if the CMTS grants the cable modem permission toenter the low-power mode, then the exemplary steps advance to step 712.In step 712, the CMTS determines parameters associated with the cablemodem's sleep cycle and sends the parameters to the cable modem. Suchparameters may include, for example, how long the cable modem ispermitted to sleep, the timing at which various timeslots and/oractivity will occur on the channel(s) while the cable modem is sleeping,the channel(s) on which the cable modem should and/or may receive and/ortransmit while in the power-saving mode, the type of signals that thecable modem may and/or should transmit and/or receive while in thepower-saving mode, and/or any other suitable parameters. The grant ofpermission may be, for example, a MAC management message wherein thecontents of its Type Value field are uniquely associated with a grant ofpermission to sleep.

In step 714, the CMTS may operate in a mode in which the timeslots 602and 604 (FIGS. 6A and 6B) are sent at independently determinable (e.g.,predetermined) intervals or times.

In step 716, the amount of time which the cable modem was supposed to bein the low-power mode has expired. Accordingly, the CMTS may expect somecommunication from the cable modem to confirm that it is still connectedto the WAN and has successfully come out of the low-power mode. In anexemplary embodiment of the invention, if the CMTS does not receive anycommunication from the cable modem within a certain amount of time, thenin step 718 the CMTS may deregister the cable modem. Conversely, if theCMTS does receive a communication from the cable modem, then in step 720the CMTS may resume a mode of operation in which the timeslots 602and/or 604 do not occur at independently determinable intervals ortimes.

FIG. 8 is a flowchart illustrating exemplary steps implemented in a CMTSfor handling a client device which supports a power-saving mode ofoperation. Subsequent to start step 802, in step 804, a cable modemconnects to the CMTS and the two devices exchange messages resulting inthe CMTS registering the cable modem. In step 806, the CMTS grants thecable modem permission to enter a sleep mode. In step 808, the CMTSswitches to a mode of operation in which management message, transmitopportunities for the sleeping cable modem, and/or contentionopportunities occur at independently determinable intervals or times. Instep 810, while the cable modem is in the low-power mode, the CMTSbuffers traffic to be transmitted to the cable modem. In step 812, uponthe amount of traffic in the buffer(s) reaching a set threshold, theCMTS may send a message to wake the cable modem from the low-power modeof operation.

Other embodiments of the invention may provide a non-transitory computerreadable medium and/or storage medium, and/or a non-transitory machinereadable medium and/or storage medium, having stored thereon, a machinecode and/or a computer program having at least one code sectionexecutable by a machine and/or a computer, thereby causing the machineand/or computer to perform the steps as described herein for server-sidehandling of a low-power client in a wide area network.

Accordingly, the present invention may be realized in hardware,software, or a combination of hardware and software. The presentinvention may be realized in a centralized fashion in at least onecomputing system, or in a distributed fashion where different elementsare spread across several interconnected computing systems. Any kind ofcomputing system or other system adapted for carrying out the methodsdescribed herein is suited. A typical combination of hardware andsoftware may be a general-purpose computing system with a program orother code that, when being loaded and executed, controls the computingsystem such that it carries out the methods described herein. Anothertypical implementation may comprise an application specific integratedcircuit or chip.

The present invention may also be embedded in a computer programproduct, which comprises all the features enabling the implementation ofthe methods described herein, and which when loaded in a computer systemis able to carry out these methods. Computer program in the presentcontext means any expression, in any language, code or notation, of aset of instructions intended to cause a system having an informationprocessing capability to perform a particular function either directlyor after either or both of the following: a) conversion to anotherlanguage, code or notation; b) reproduction in a different materialform.

While the present invention has been described with reference to certainembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the scope of the present invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the present invention without departing from its scope.Therefore, it is intended that the present invention not be limited tothe particular embodiment disclosed, but that the present invention willinclude all embodiments falling within the scope of the appended claims.

What is claimed is:
 1. A method comprising: in a cable modem termination system (CMTS) of a Data Over Cable Service Interface Specification (DOCSIS) network: receiving a request that a network device be permitted to enter a power-saving mode of operation; in response to said request, entering a power-saving mode of operation which comprises transmitting a message granting said network device permission to enter said power-saving mode of operation, wherein said message granting said network device permission to enter said power-saving mode of operation is a Moving Picture Experts Group (MPEG) transport stream packet having a first program identifier (PID) that: is uniquely associated with messages that manage power consumption in the DOCSIS network; and is different from a second PID used for MPEG transport stream packets that carry DOCSIS messages.
 2. The method of claim 1, wherein said network device is a cable modem, cable set-top-box, or cable gateway.
 3. The method of claim 1, comprising: while operating in said power-saving mode of operation, starting a sleep timer upon transmitting a media access control (MAC) management message.
 4. The method of claim 3, wherein said MAC management message comprises a MAP and/or upstream channel descriptor (UCD) message.
 5. The method of claim 3, comprising deregistering said network device if no communication is received from said network device prior to expiration of said sleep timer.
 6. The method of claim 3, comprising determining a value at which said sleep timer expires based on network traffic statistics.
 7. The method of claim 1, wherein: said request is a media access control (MAC) management message; and contents of a type value field of said request are uniquely associated with requests for permission to enter a power-saving mode of operation.
 8. A method comprising: in a host device that centrally manages access of a plurality of Data Over Cable Service Interface Specification (DOCSIS) client devices to a shared medium comprising one or more coaxial cables and/or fiber optic cables: receiving, from one of said client devices via said one or more coaxial cables and/or fiber optic cables, a request that said one of said client devices be permitted to enter a power-saving mode of operation; in response to said request, entering a power-saving mode of operation which comprises transmitting a message granting said one of said client devices permission to enter said power-saving mode of operation, wherein said message granting said one of said client devices permission to enter said power-saving mode of operation is a Moving Picture Experts Group (MPEG) transport stream packet having a first program identifier (PID) that: is uniquely associated with messages that manage power consumption in the DOCSIS network; and is different from a second PID used for MPEG transport stream packets that carry DOCSIS message.
 9. The method of claim 8, comprising: buffering traffic destined for said one of said client devices in a buffer of said host device while said one of said client devices is in said power-saving mode of operation; and upon an amount of traffic stored in said buffer reaching a threshold, transmitting a message to trigger said network device to transition out of said power-saving mode of operation.
 10. A system comprising: circuitry for use in a cable modem termination system (CMTS) of a Data Over Cable Service Interface Specification (DOCSIS) network, wherein said circuitry comprises at least one networking circuit for use in transmitting and/or receiving of signals and at least one control circuit for performing control operations based on transmitted and/or received signals, said circuitry being operable to: receive, via said at least one networking circuit, a request that a network device be permitted to enter a power-saving mode of operation; in response to said at least one control circuit processing said request, enter a power-saving mode of operation in which a message granting said network device permission to enter said power-saving mode of operation is transmitted, wherein said message granting said network device permission to enter said power-saving mode is a Moving Picture Experts Group (MPEG) transport stream packet having a first program identifier (PID) that: is uniquely associated with messages that manage power consumption in the DOCSIS network; and is different from a second PID used for MPEG transport stream packets that carry DOCSIS messages.
 11. The system of claim 10, wherein said network device is a cable modem, cable set-top-box, or cable gateway.
 12. The system of claim 10, wherein, while in said power-saving mode of operation, said circuitry is operable to start a sleep timer upon transmitting a media access control (MAC) management message.
 13. The system of claim 12, wherein said MAC management message comprises a MAP and/or upstream channel descriptor (UCD) message.
 14. The system of claim 12, wherein said circuitry is operable to deregister said network device if no communication is received from said network device prior to expiration of said sleep timer.
 15. The system of claim 12, wherein said circuitry is operable to determine a value at which said sleep timer expires based on network traffic statistics.
 16. The system of claim 10, wherein: said request is a media access control (MAC) management message; and contents of a type value field of said request are uniquely associated with requests for permission to enter a power-saving mode of operation.
 17. The system of claim 10, comprising buffering traffic destined for said network device in a buffer of said CMTS while said network device is in said power-saving mode of operation.
 18. The system of claim 17, wherein said circuitry is operable to, upon an amount of traffic stored in said buffer reaching a threshold, transmitting a message to trigger said network device to transition out of said power-saving mode of operation. 